Coach Kou
by FujiAppleQueen
Summary: Rin, Haruka and crew are in second grade. Their swim coach has to leave for a few days and needs a substitute for his class. Rin's big sister Kou is chosen for the job, but can she handle her little brother and his friends? AU for age changes.
1. Chapter 1

It had been the second summer that Kou had worked for the local swimming club. On top of going to school, she held part times jobs from time to time. Whenever she was available, Sasabe would invite her to return working for him as a lifeguard during the peak season of the year. Her little brother, Rin, was excited to find out that his big sister was going to work at the swim club he attended. He joined the club around his kindergarten year and had returned ever since. Just like his little friends Haru, Makoto and Nagisa, Rin loved splashing around the water, challenging Haru to races or playing sharks and minnows with the others. Kou preferred to work by her brother, just in case he needed some extra discipline. There had been more than few times previously where Coach Sasabe would have to call home to report that Rin had bitten someone or made other trouble.

Kou arrived at the club a little earlier than usual; Sasabe needed to talk to her about something before the pool opened that day. Rin didn't seem to mind; once they got inside, he dashed toward the locker rooms with his little shark bag in tow. Arriving early to the pool became a nice little perk that he enjoyed. "Stop running by the pool!" Kou shouted. She wasn't even on duty and she had to remind her brat brother not to break the rules. Rin just ran faster and disappeared to the hall that led to the changing rooms. Sighing, she entered the staff rooms to drop off her things.

"Afternoon, Kou. I see that your brother is on his best behavior," Sasabe jeered, looking up from his clipboard. The teen rolled her eyes at her boss.

"_You're _his coach, you should know how he acts," she retorted, putting on her whistle and badge. Kou usually got dressed in her regular uniform and swim attire before arriving to work. The older man chuckled, putting down his paper work.

"Speaking of which," Sasabe started "How would you like to sub for my swim class for a few days?" Kou looked at him with wide eyes.

"Is this what you called me in for?" Kou asked. Sasabe gingerly rubbed the back of his neck.

"Yeah well… I need someone to watch over my class while I'm away for the swim league conference. I figured, since I coach your brother's class, that you'd be a good fit. You know the kids already since you've been here for a while…" Kou put a hand on her hip and looked at him with disbelief. Sure, she was his older sister, but she didn't feel qualified to coach a group of seven year olds how to swim.

"No offense coach, but I could barely teach my brother how to tie his shoes. Besides, I _kinda_ know his friends." Sasabe smirked in amusement.

"It'll be easy! I'll give you list of the drills, what to focus on with who and such. There's even a bunch of games they know how to play already. You just ask them what they wanna do and then go do it. Heck, you can even have a little 'free play' time at the end of the lesson," Sasabe started to dig through his messy desk, searching for the lesson plan he was talking about. He made a noise of approval when he found it, handing it to Kou.

Kou's dark red eyes scanned the items on the list. Really, it looked more like a reference sheet that Sasabe would use if he needed an activity to burn time. She wouldn't put it past him if he allowed them to have "free play" time every day.

"When would I start?" she asked, folding the sheet of paper. The blonde smiled nervous, which did not make Kou feel any better.

"Err…tomorrow. And I'll be gone for three days."

"Tomorrow?! Three days?!" Kou shouted, irritated that her boss would procrastinate like this. Sasabe held his hands up in defense.

"Trust me, Kou, if I could tell you sooner I would. My original sub cancelled on me and I didn't know what to do! Please, I'll owe you big time if you could do this for me. Please?" The older man smiled sheepishly, hoping that she would say yes. Folding her arms across her chest, Kou pressed her lips together and looked at him with narrow eyes.

"Fine!" Kou sharply turned her head to the side as her boss cheered.

Meanwhile, Rin sat by the poolside, his feet dipped in the water. Kou had a rule that he couldn't go in unless there was another life guard around. It was for safety, or something. Rin didn't care; he was old enough to swim all by himself. He could go into the deep end even! Only big kids got to do that. But he'd rather not get in trouble with Kou, and then have her report home that he was being naughty. Rin slouched in boredom, blowing his bang away from his face. _'What's taking her so long? I'm so boorreddd.'_ Normally, he would be in the water by now, swimming before any of the other kids even finished changing. He enjoyed his special pool privileges, although he would like to share it with his best friend Haruka. Rin growled in annoyance when the staff opened the pool doors to the public. So much for having private swimming time.

By the time the lifeguards attended their posts, Haruka, Nagisa and Makoto had joined Rin on the poolside.

"Rin-chan!" Makoto greeted with a bright smile. "How come you're not in the pool already?" Makoto was unaware of the fact that his sister worked for the club. He was lead to believe that Rin had some sort of magical pool pass that allowed him to go swimming before anyone else. Rin pouted, turning away from his friend without saying a word.

His scowl soon turned into a grin. "C'mon! Let's do our warm ups!" Rin slipped into the cool water; his friends following right after. Coach Sasabe emerged out of the staff room with Kou, briefing her on his class.

"…Nagisa can be super friendly and likes physical contact, so be careful. Rin and Makoto like to fight over who gets to be partners with Haruka, so just have Haru pair up with Nagisa. Haruka only swims freestyle or he cries, so don't try to force him to do anything else. And you should know about Rin's biting problem…" Kou glanced over to the pool while still listening to Sasabe, walking with him towards his class. She had seen her brother's friends before, but only as other students of the club. She vaguely remembered them coming over; it was usually Rin who left to play at his buddy's house. She was most familiar with Haruka, only because Rin would babble on and on about him. Four little heads popped out of the water, all of them staring at her and Coach Sasabe as they approached. Kou smiled softly at the boys, finding them all awfully adorable together. Sasabe gestured for the boys to swim closer to the pool's edge.

"Coach Sasabe! Coach Sasabe!" Nagisa greeted, swimming to the poolside wall. His bright pink eyes turned to look at Kou. "How come you're with Rin's sister? Are you daaattinngg?" Nagisa giggled. Makoto giggled along with him, finding the prospect of their coach having a girlfriend funny. Hakura's deadpan facial expression didn't change. Rin shot a glare at Nagisa.

"No! I'd go to jail if I did!" Sasabe replied hastily. The boys looked at him curiously as the comment sailed over their little heads. Kou put her hand on her forehead, shaking her head at her boss's idiocy. Sasabe cleared his throat, and then gestured to Kou. "I have to leave for a few days starting tomorrow, so uh, Coach Kou will be teaching you guys while I'm gone."

Rin grinned brightly, throwing his little hands in the air. "Yay! Big sis is gonna be our coach! My sister's the best!" Kou giggled at the praise she was receiving. It was obvious that they had a very strong sibling bond. Nagisa cheered alongside Rin, reaching out and grabbing Kou's ankle. "Coach Gou! Cool!" Kou didn't have the heart to correct the boy, so she let the mistake slide for now. She gently pried his little hands off her ankle while a nervous smile on her face. The last thing she needed was a little boy clinging onto her.

"We're gonna miss you, Coach Sasabe," Makoto said, looked up at him with sad eyes. The blonde man sighed. Makoto had a more difficult time dealing with people he wasn't familiar with. He knelt down and patted the young boy on the head.

"Don't worry, I picked a really nice coach for you guys okay? I wouldn't leave you with just anybody." His words seemed to ease Makoto's nervousness. "Beside, she's Rin's sister. Rin's your friend right?" The brunette nodded timidly. As if on cue, Rin swam to Makoto's side.

"She's really cool, Mako. You'll like her." He put an arm around the taller boy, grinning brightly. "Ne ne, big sis, does that mean I get to be assistant coach?" He turned to look up at Kou with big, brilliant ruby eyes. Kou wrinkled her nose, immune to his charms.

"No," she answered curtly. Rin pouted, sticking his tongue out at her.

"Well, she's _kinda _cool," he mumbled to Makoto, who only nodded. Kou shot a look over to Sasabe.

"Aren't they cute?" he commented, standing up. Kou sighed, making her way to her post.

"Yeah, _real_ cute."

**A/N: Thanks for reading! Please let me know what you think! **


	2. Chapter 2

**A/N: Thanks everyone who reviewed! I'm so glad you guys like the fic. Special thanks to beta reader Nerumi H for helping me out! I struggled with this chapter and her feedback was super helpful. Anyways, enjoy! **

Kou found that she felt a bit nervous when she entered the swimming club. Her experience with teaching was limited, but she tried to reassure herself that it would be similar to being a lifeguard. Make sure nobody drowns and that the students are doing something. Rin tried once more to run on the pool deck, but Kou's threat about kicking him out of her class put a stop to that. She technically was his teacher for the remainder of the week, so she did have a say on who got to participate in class and who had to sit out. Begrudgingly, Rin walked to the locker rooms to put his things away. Kou stepped into the staff room and saw another lifeguard getting ready for his shift.

"Hey Hiroki," Kou greeted, her voice not as cheery as normal. Her coworker perked his eyebrows up.

"Hey Kou. Feeling nervous about teaching the kiddies?" The staff had been notified about Sasabe's trip. He also let them know who was taking over his class. To Kou's surprise, he scheduled someone to cover her regular lifeguard shift. She figured that he would've let that detail slip.

"Yeah, a bit," she replied, looking over the notes her supervisor left.

"You'll do just fine." She looked at him, unconvinced. With a grin he whispered, "Hey, if Sasabe can do it, so can you." Kou stifled a small laugh and rolled her eyes. It _did_ make her feel a bit better, though. Sasabe was an experienced coach, but there were some times when Kou worried about his teaching methods.

"Thanks," she smiled, picking up her things and walking over to her designated class area. The shallow end of the pool was reserved for the young swimmers. There were usually two to three classes going at a time. Her section was divided by a string of buoys to prevent her class from mingling with the others. The lanes and the diving well were left for the older students. Once in a while, one of the little ones would try to cross into the lanes. Their attempts were never successful, due to the vigilant eyes of the staff there. Rin had a thing about wanting to swim with the big kids, but Kou refused to let him do so. She believed that he was more than capable to handle himself in the deep ends, but it was against the rules.

Once Rin saw his sister exit the staff room, he dove into the pool with great excitement. He respected Coach Sasabe, but he was really looking forward to having his sister run the class. "C'mon Kou, come in the water! That's what Coach Sasabe does when he teaches us!" He figured that his sister might need a little bit of his help on what to do during swim class. Kou smirked in amusement, walking over to a bench by the pool and putting her stuff down. Her brother had his adorable moments, she had to admit.

"I'm coming," she answered, readjusting her bun. After grabbed some supplies for the day's activities, the redheaded teen gingerly slipped into the chilly water. The water came up to Kou's waist when she stood. Rin took the opportunity to jump on his sister's back and hung on. "Rin!" Kou scolded, jumping at his surprise attack. Her little brother grinned a big toothy grin.

"I can't wait to play with you, sis!" Even though she worked at the pool, it was rare when Kou would go and play with him. Unfortunately for the both of them, she couldn't really mess around. It was easy to see that Rin figured he could play with her during swim class. Kou took his hands and removed them from her shoulders, turning to face him.

"Rin-chan, I can't play with you yet. I still have to teach," she sighed, letting go of his hands. Rin looked to the side, clearly disappointed. Kou furrowed her brows together. She didn't like seeing her baby brother upset, but she had a job to do. Before long, the doors to the indoor pool opened and the students started to come in.

"Look, Rin, your friends are coming," Kou commented, smiling softly as she tried to cheer him up. Rin's big round eyes peered up over the pool's edge. Indeed his classmates had arrived, all dressed for a day at the pool. Kou took a deep breath, mentally going over the simple lesson plan she had developed the night before. According to Sasabe, the boys already knew a lot of the major strokes. He wanted to focus more on endurance and technique for now. Kou figured that kick board practice, a breathing exercise and a few games would suffice.

Rin waved at his group of friends. "Come on in guys! My sister's already here!" Haruka didn't need an invitation. The blue-eyed boy calmly walked over to the poolside and jumped right in. Kou even caught the boy smiling when he entered the water. Makoto sat on the concrete edge before sliding in.

"Hi Coach Kou," he greeted, giving her a friendly smile. He seemed less nervous than he was the previous day. Kou smiled back.

"Good afternoon, Mako-chan. Are you ready for swim class today?" He looked over to Rin and Haru, who were both hanging onto the wall. Rin gave him a thumbs up and wink, for encouragement. Haru stared at Mako, giving him a small nod.

"I think so," Makoto answered innocently, latching onto the wall as well. Kou resisted the urge to squeal; she couldn't help but find his shyness adorable.

"I could've sworn there was one more kid," the teen mumbled to herself, placing a finger on her chin. And that's when it hit her.

Well, more like that's when he _landed_ on her.

Nagisa thought along the same lines as Rin when he first saw her in the pool. The blonde boy felt that jumping on his substitute coach was a great way to welcome her to the class.

"Coach Gouuu!" he cried after landing on his target. His little arms wrapped around her neck. He was lucky that she could keep her balance or else they would've both ended up underwater. He was also lucky that Kou had the reflexes to catch the kid.

"Nagisa!" she chided, frowning. Did the kids to that to Sasabe on the regular? "You can't do that, that's not okay," she instructed, albeit a little more forcefully than she intended. She pulled the boy off her torso and put him by the wall with the rest of his class. The blonde child stuck out his bottom lip and looked at her with wobbly eyes.

"I'm sorry, coach. I-I got excited," he replied honestly. "Coach Sasabe lets us hang off of him sometimes."

Kou tried her best not to look annoyed. She didn't want to upset Nagisa for something he had no control over. She made a small mental note that she needed to talk to her boss about proper classroom etiquette. She should've known that Sasabe would allow kids to climb all over him. Hell, she'd even seen it a few times. She didn't think he would do it enough that the kids would think it was normal behavior. She took a second to gather her thoughts and reminded herself that she could relax a little bit with the kids. She wasn't on super serious lifeguard mode. She only had to monitor a few students after all.

"What are we doing today sis?" Rin asked with bright eyes. The boys looked to Kou and waited for further instruction. Her nerves started to slowly creep back again, but she didn't let them interfere with her work.

"Well, we'll do some warm ups, kickboard practice and, if you guys are good, we'll play some games at the end. How's that sound?"

The cheer she received from the boys made her feel a little more confident about teaching the class.

In her short career as a lifeguard, she had never been so tired during a shift. Never.

Sure, she could handle going to school, working by the pool and returning home to deal with Rin. But to manage a group of seven year olds? Even if there were only four of them? She had developed a new respect for Sasabe.

The kids were done with everything she planned for in less than half an hour. Rin, of course, wanted to play Sharks and Minnows, but Nagisa decided to argue with him. He wanted to play Marco Polo instead. Kou found out the hard way that Nagisa was just as bull headed as her little brother. The two boys ended up in a vicious splash fight, scaring Makoto into tears (he didn't like seeing his friends fight). Haruka was mature enough to pull Makoto to the side and comfort the boy. Kou literally had to pull Rin and Nagisa apart before things started to get really out of hand. She sent them to sit on opposite ends of the poolside bench, as punishment for making such a ruckus.

And that all happened under fifteen minutes.

"Mako-chan?Are you okay?" Kou asked gently, floating over to the teary eyed child. Makoto sniffled a few times before nodding. Haruka was patted him on the head, his eyes filled with concern. The teen could tell that Haru was very protective of his little friend. It was no wonder why Rin spoke so highly of him.

"Coach Kou, can we do free swim?" Haru asked with a monotone voice. She was shocked to hear him speak a full sentence. For one reason or another, this child rarely said anything beyond three words.

"O-only for a little bit. And stay within the boundaries." The raven-haired child nodded. He glanced over to Makoto, silently encouraging him to swim. The taller boy gave him a small smile before swimming alongside his friend. Kou was baffled to see that the boys could communicate without speaking. 'Kids are so weird sometimes,' she mused. She turned her attention back to the troublemakers on the bench. She fought the urge to spank Rin in front his friends, though she knew that it would teach him.

"We wouldn't be here if you would've let us play Sharks and Minnows without arguing," Rin growled, glaring at the blonde. Nagisa frowned.

"We always play that game. I thought it would be fun to play something different."

"Well, you're stupid."

"You're a bully!"

"Shut up!"

"Stop it you two!" Kou shouted, coming out of the pool. She knelt down in order to get eye level with the boys. In a steadier, motherly voice, she said, "You guys are supposed to be friends. If you want to get back in the pool, you're going to have to make up."

Both boys were silent, but Nagisa decided to make the first move. Rin kept his arms folded across his chest, scowling. Apologies were never his strong suit, especially at this age. For Nagisa, however, he would rather make up and continue swimming. Without much hesitation, the blonde hopped off the bench and gave him a hug. Rin didn't reciprocate, causing Nagisa to hug him harder, pressing his cheek against the sharkboy's face.

"Riiiiinnn I'm sorry," Nagisa said, rubbing his face against Rin's. The ruby haired child kept his lips shut, though Kou could tell that he was starting to soften up. The influence his friends had on him was something she hadn't seen before. Usually, he demanded solitude whenever he threw his fits. Cuddling, he claimed, was for "babies". And yet, she watched her brooding baby brother being snuggled by another child. Kou's lips curled into a small smile.

Nagisa released him from his hug and poked the taller boy on the forehead. "Tag, you're it!" Much to Kou's displeasure, the smaller boy ran and jumped into the pool.

"Nagisa!" Kou shouted. Before she could say anything else, Rin dashed off the bench and chased after him. "Rin!" She reached out to stop her kid brother, but was unsuccessful. Irritated, she stomped over to the water's edge. The last thing she needed was to see her brother enter a second fight. Instead of screaming, though, she heard her brother and his friend giggling.

"You're gonna get it, Nagisa!" Rin laughed, swimming after the blonde. Makoto and Haruka decided to join in the game as well. Soon, her class regained its harmony with all the kids playing with each other. Kou sighed as she slipped back into the pool. _'It was like nothing ever happened.'_

Her class only ran for about an hour, thank goodness. The kids were released to play in the pool for the rest of the day. Kou resumed her post as a lifeguard until it was time for the pool to shut down. Although she kept an eye on the general public, she found herself checking up on her small class more often than not. Slowly, there were less and less people in the pool as the day continued. Once the closing announcements were made, the remaining attendants started to step out of the pool.

Except for Rin.

Rin floated over to the side where his sister was standing guard. His friends grabbed their little towels and began to dry off, until they heard Rin ask a very interesting question.

"Hey big sis, is tomorrow your long shift?" Kou and the other lifeguards took turns closing the pool, so once a week, Kou would have to stay a half hour longer to clean up. During that time, she allowed Rin to stay in the water until their mother came to pick them up. It was the best day of the week for Rin, because the building was pretty much empty during that time.

Kou looked at her little brother with a raised eyebrow, unaware of what was going to happen next.

"Yeah, it's tomorrow," she replied casually. She knew he liked her long shift days. One of them had to.

"Yes! I get an extra thirty minutes!" Rin happily swam to the staircase, the message echoing throughout the pool.

Haruka dropped his towel and stared at the approaching shark boy with wide eyes. An extra thirty minutes in the water? To a seven year old, that was a really long time. Really long. Makoto and Nagisa also marveled at the luck Rin received for having his sister work at the club.

"Wow Rin-chan, you can stay extra long tomorrow?" Makoto asked, excited for his friend. The ruby-haired child flashed a grin.

"Yup! Every week!" he announced his hands on his hips. "And I get the whooole pool to myself!" Before long, his friends started to crowd around Kou, begging and pleading to stay as well.

"Please Coach Gou! We'll be good! We'll follow the rules and everything!" Nagisa begged, his rose-colored eyes wide and sparkling. Kou could've sworn that he probably practiced that look to sucker adults into doing what he wanted.

"You're supposed to follow the rules, Nagisa," she retorted, but his face didn't change. "And call me Coach Kou."

"Please, Miss Coach Kou, please can we stay tomorrow?" Makoto clasped his little hands together and looked up at Kou with bright green eyes. The double title he gave her was stupidly cute. Were kids normally that cute on a regular basis? Kou's defenses were wearing down; she felt like caving in soon. Then she made the mistake of looking at Haruka.

Haruka said nothing during the commotion; he didn't have to. Kou was met with large, round cerulean eyes, full of hope and happiness. The way he looked at her gave her the notion that if she were to say no, he would be devastated and his little life would be ruined. Those pleading blue eyes pierced her final defense. She _couldn't_ say no, now.

Closing her eyes, she put her hand on her face before mumbling, "Ask your parents first." A loud cheer erupted from the boys. Hugs and smiles were exchanged in celebration. Haruka smiled as well, holding hands with his friends as they made their way to the locker room.

"Aww, that was awfully nice of you, Miss Coach Gou," Hiroki teased from across the deck. Kou made a face at her laughing co-worker.

"It's Kou! You know better!" she shouted in a huff, her fists clenched tightly by her side. Teenage boys could be so irritating.

"Are you going to let the other kids stay back too?" Kou looked at him quizzically. Other kids?

"What other kids?" she asked tentatively. Hiroki flung his towel over his shoulder and walked over to Kou.

"Yeah. Sasabe didn't tell you? He's got three new students coming in tomorrow." Kou stared at him, not wanting to believe what she heard. She felt her eye twitch involuntarily. Three more students? That almost _doubled_ her class size.

"I have to make a phone call," she said to no one in particular. Judging by her darkened expression, Sasabe was in a whole lot of trouble.

**A/N: Can you guess who the new students are? Can you? *dances* :D**


End file.
